During coal face operations, methane and respirable dust are generated both of which constitute serious safety and health hazards. The most effective technique for controlling these hazards has been to maintain adequate ventilation in the area of the mine face. One technique for doing this involves the use of tubular piping to provide the appropriate ventilation. For example, in U.S. Pat. No. 963,787 (Martin) and in U.S. Pat. No. 3,289,567 (Renner), mine ventilating systems are disclosed in which a conduit is used to direct air to the area of a mine face. Further, U.S. Pat. No. 3,919,930 (Yoskikawn et al) provides an air supply duct for a mine face on a movable carriage. Another conventional method of directing air to a mine face is through the use of brattice curtains. For example, U.S. Pat. No. 3,636,852 (Burgess, Jr.) discloses the provision of brattice curtains to create a flow path for ventilating air to the mine face.
While these prior art techniques have been generally successful, a number of disadvantages result from their use. One disadvantage of these methods is that the apparatus employed may take up too much room in a small tunnel and thus is likely to be damaged by the face equipment in the tunnel. Also, such systems are time consuming to set up. Further, as regards the brattice curtains, such curtains cannot be readily extended beyond the last roof bolts which thus limits their effectiveness.
Recent studies have indicated that a satisfactory ventilation system can be achieved by combining a blowing system and a machine mounted scrubber. This is especially true with recently developed "full face" machines and in situations where the mining machine penetrates more than twenty feet. However, blowing tubing used in conjunction with this technique is frequently too cumbersome and difficult to maintain and suffers the same disadvantages with regard to the amount of space occupied thereby.